Sauna health benefits: what the research shows
Regular sauna bathing is linked to a healthier heart and a lower risk of dementia. Most of that evidence comes from one long Finnish study of middle-aged men, so here is what was found, how much weight it can bear, and who should be careful.
In short
- Finnish men who used a sauna more often had fewer fatal heart attacks and less dementia over about 20 years of follow-up.
- These studies show an association, not proof that the sauna caused the difference.
- The heat does measurably affect blood vessels and blood pressure, which gives a plausible explanation.
- For most healthy adults sauna bathing is safe. Alcohol is the main danger.
The study behind most headlines
Much of what is written about sauna and health traces back to the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) in eastern Finland. It enrolled 2,315 men aged 42 to 60 between 1984 and 1989, recorded how often they used a sauna, and then followed their health for about two decades.
What the research found
| Outcome | Finding | Evidence |
|---|---|---|
| Fatal heart disease | Compared with once a week, men who used the sauna 2–3 times a week had about 23% lower risk of fatal coronary or cardiovascular disease, and those using it 4–7 times a week about 48% lower. Sudden cardiac death and death from all causes were also lower with more frequent use. | Stronger |
| Dementia and Alzheimer's | Men using the sauna 4–7 times a week had about a third of the dementia and Alzheimer's risk of once-a-week users. The 2–3 times a week group was not clearly different. | Limited |
| Blood pressure and arteries | Heat exposure widens blood vessels, reduces arterial stiffness and lowers blood pressure in experimental studies, and frequent use is linked to less high blood pressure. | Limited |
| Lungs, joints, colds, headache | A 2018 review lists associations with fewer lung diseases and relief of arthritis, headache and flu symptoms. The studies are smaller and less consistent. | Early |
"Stronger" here means a large prospective study with long follow-up, still observational. "Limited" means fewer cases, short-term experiments or a single cohort. "Early" means small or inconsistent studies.
Why the numbers need care
- Association, not cause. People who can take a sauna every day may be healthier, wealthier or more relaxed to begin with. The researchers adjusted for known risk factors, but no observational study can rule this out. They themselves called for randomised trials.
- Who was studied. Middle-aged Finnish men from the 1980s, in a culture where a hot, traditional sauna is routine. Results may differ for women, younger people, infrared cabins or occasional gym saunas.
- Frequency was measured once. Sauna habits were recorded at the start and not updated over twenty years.
Why it might work
A hot sauna raises skin temperature and heart rate and widens the blood vessels. A 2018 review in Mayo Clinic Proceedings by the same research group describes the likely mechanisms: better function of the blood vessel lining, lower arterial stiffness, changes in the autonomic nervous system, improvements in blood lipids and lower blood pressure. These effects are measurable in short-term studies, which is why researchers consider the long-term associations plausible.
Who should be careful
A review in the American Journal of Medicine found sauna bathing well tolerated by most healthy adults and children, and generally safe for people with stable heart disease. It named three situations where sauna bathing should be avoided:
- unstable angina (chest pain that is new, worsening or comes at rest)
- a recent heart attack
- severe aortic stenosis
The same review considered sauna bathing safe in an uncomplicated pregnancy. If you are pregnant, have a heart condition or take blood pressure medication, ask your doctor or midwife what is right for you.
Alcohol is the real risk
Drinking and sauna do not mix. Alcohol makes it harder for the body to hold blood pressure in the heat, which leads to fainting, falls, burns and, at worst, heart rhythm problems. A Finnish paper from 1988 estimated that alcohol played a part in roughly 20 to 25 sauna-related deaths a year in Finland. Skip the sauna after drinking and during a hangover.
Practical habits
- Drink water before and after, since you lose fluid by sweating.
- Leave when you feel dizzy, nauseous or unwell. There is no target time to reach.
- Cool down gradually and sit for a moment before standing up quickly.
- Supervise children and keep their sessions shorter and cooler.
Sources
- Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Internal Medicine, 2015. Summarised in van der Wall EE, Netherlands Heart Journal, 2015.
- Laukkanen T, Kunutsor S, Kauhanen J, Laukkanen JA. Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men. Age and Ageing, 2016. University of Bristol record
- Laukkanen JA, Laukkanen T, Kunutsor SK. Cardiovascular and other health benefits of sauna bathing: a review of the evidence. Mayo Clinic Proceedings, 2018;93(8):1111–1121. University of Bristol record
- Hannuksela ML, Ellahham S. Benefits and risks of sauna bathing. American Journal of Medicine, 2001;110(2):118–126. Abstract
- Ylikahri R, Heikkonen E, Soukas A. The sauna and alcohol. Annals of Clinical Research, 1988;20(4):287–291. PubMed